A conventional refrigerator employs a refrigeration cycle using a compressor. The compressor is used for condensing a working refrigerant in the refrigeration cycle. The condensed working refrigerant is reduced in pressure and expanded in an expansion portion, and is delivered to an evaporator. The evaporator attains a low temperature as the working refrigerant evaporates therein. The evaporator is arranged inside the refrigerator, and the interior of the refrigerator is maintained at a low temperature by the evaporator. For the working refrigerant, an alternative refrigerant (HFC refrigerant) or hydrocarbon (HC refrigerant) is used.
A refrigerator provided with a Stirling refrigerating machine using a reversed Stirling cycle instead of the refrigeration cycle using the compressor has been proposed (e.g., Japanese Patent Laying-Open No. 2000-18748). A refrigerator incorporating both the Stirling refrigerating machine and the compressor has been proposed as well.
FIG. 4 is a schematic cross sectional view of a refrigerator incorporating a Stirling refrigerating machine and a compressor that is disclosed in Japanese Patent Laying-Open No. 2000-337747. The refrigerator is partitioned into a cooling compartment 21 and a freezing compartment 22, with freezing compartment 22 being arranged on the upper side and cooling compartment 21 being arranged on the lower side. A compressor 11 is arranged in the back at the bottom of cooling compartment 21. The refrigerant compressed by compressor 11 is delivered via a first circulation circuit 5 to a heat exchanger 29. Cooling and expansion of the refrigerant take place (not shown) between compressor 11 and heat exchanger 29. The refrigerant having reached heat exchanger 29 is evaporated within heat exchanger 29, which cools heat exchanger 29 by latent heat. The refrigerant having been evaporated in the cooling compartment evaporator is returned via first circulation circuit 5 to compressor 11, where it is compressed again.
At the back of cooling compartment 21, a cooling compartment circulation path 8 is formed for circulation of the air in cooling compartment 21. Heat exchanger 29 is arranged inside cooling compartment circulation path 8. Also arranged in cooling compartment circulation path 8 is a cooling compartment cooling fan 23. As cooling compartment cooling fan 23 is driven, the air flow occurs inside cooling compartment circulation path 8. In FIG. 4, the air in cooling compartment 21 enters cooling compartment circulation path 8 from the lower side and is released into cooling compartment 21 from an outlet formed in cooling compartment circulation path 8. The air within cooling compartment 21 is cooled as it comes into contact with heat exchanger 29 when passing through cooling compartment circulation path 8. The air coming out of cooling compartment circulation path 8 has been cooled and is of a low temperature. This air flow cools the items stored in cooling compartment 21.
Stirling refrigerating machine 1 is arranged in the back at the top of the refrigerator. Stirling refrigerating machine 1 is a device in which a piston performs a reciprocating motion inside the cylinder, which causes the working refrigerant to move between a compression space and an expansion space to thereby repeat compression and expansion. As the working refrigerant, helium gas, hydrogen gas, nitrogen gas or the like is filled therein. The working refrigerant compressed in the compression space is at a high temperature, which is cooled by the outside air at a high-temperature heat radiation portion 2. The cooled working refrigerant is expanded as it is transferred to the expansion space. The working refrigerant attains a low temperature as it is expanded in the expansion space. The working refrigerant of a low temperature cools a low-temperature heat absorption portion 3. Low-temperature heat absorption portion 3 is formed such that a part thereof is exposed to freezing compartment 22. Freezing compartment 22 is cooled by low-temperature heat absorption portion 3.
In the refrigerator shown in FIG. 4, cooling compartment circulation path 8 extends to the top portion of the refrigerator where Stirling refrigerating machine 1 is arranged. Further, a blower fan 25 is arranged to deliver the cool air toward the top portion of the refrigerator. This refrigerator is configured such that driving of bower fan 25 can deliver a part of the air cooled by heat exchanger 29 to the high-temperature heat radiation portion of the Stirling refrigerating machine. High-temperature heat radiation portion 2 is cooled by this air of a low temperature. The air having cooled high-temperature heat radiation portion 2 is externally discharged via an exhaust vent 26 formed on the backside of the refrigerator.
Since this refrigerator has freezing compartment 22 cooled by Stirling refrigerating machine 1 and cooling compartment 22 cooled by heat exchanger 29, the respective compartments can be used in accordance with the intended use, so that a refrigerator of high usability is obtained. Further, the air in cooling compartment circulation path 8 having been cooled by heat exchanger 29 can cool high-temperature heat radiation portion 2 of Stirling refrigerating machine 1, and as a result, cooling efficiency of Stirling refrigerating machine 1 is improved.
Patent Document 1: Japanese Patent Laying-Open No. 2000-18748 (pages 4-5, and FIGS. 1-6)
Patent Document 2: Japanese Patent Laying-Open No. 2000-337747 (pages 3-4, and FIGS. 1-2)